JPH0378516A - Exhaust muffling device for ship propulsion machinery - Google Patents

Abstract

PURPOSE:To achieve muffling of an exhaust noise certainly and efficiently, by providing a first expansion chamber, a pair of second expansion chambers communicating thereto, and a third expansion chamber communicating to each second expansion chamber respectively through a pair of communicating ports opposing to each other. CONSTITUTION:Exhaust from an engine 12 in a propulsion machinery for a small ship, is led to an exhaust muffling device 32 through an exhaust manifold 22, a large diameter exhaust pipe 24, and an exhaust hose 28, and after a noise reduction discharged into the atmosphere through an outlet pipe 60. In this occasion, the exhaust muffling device 32 is constituted in a box type casing 34, by providing a first expansion chamber 40, a pair of second expansion chambers 42, and a third expansion chamber 44, which are partitioned by a first partition plate 36 crossing the longitudinal direction of a casing 34 and a pair of partition plates 38 extending in the longitudinal direction of the casing 34. A pair of second expansion chambers 42 are communicated to the first expansion chamber 40 through a pair of communicating ports 46, and each of the expansion chambers 42 is communicated to the third expansion chamber 44 through a second communicating port 48.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an exhaust silencing device for a marine vessel propulsion device.

[Prior Art] Conventionally, in marine propulsion systems, exhaust silencing devices have been provided for the purpose of reducing the noise of exhaust gas discharged from the engine. As this exhaust silencer, for example,
- As described in Publication No. 137635, Japanese Patent Application Laid-open No. 55-25566, etc., an expansion chamber is provided in the middle of the route for exhaust exhaust to the outside of the ship, and the exhaust is expanded in this expansion chamber to muffle noise. 1 For example, Utsukai 53-982
As described in Japanese Patent Application No. 35, etc., there was one in which a resonance type exhaust silencing device was provided in the exhaust route.

[Problems to be Solved by the Invention] However, although the exhaust gas expansion chamber shown in the above-mentioned prior art is a two-stage expansion chamber, a sufficient sound deadening effect cannot be achieved only by sound deadening by such expansion of the exhaust gas. Similarly, a resonance type muffling device also has a problem in that effective muffling cannot be expected.

The present invention was made in view of the problems of the prior art, and its purpose is to provide an exhaust silencing device for a marine propulsion machine that can more reliably and efficiently achieve exhaust silencing. There is something to do.

[Means for Solving the Problems] In order to achieve such an object, the present invention provides a first expansion chamber into which exhaust gas from an engine is introduced, and a pair of second expansion chambers each communicating with the first expansion chamber. and a third expansion chamber having a pair of communication ports facing each other and communicating with the pair of second expansion chambers via the pair of communication ports.

[Function] As described above, the exhaust silencer is connected to the first expansion chamber and the second expansion chamber.
By comprising an expansion chamber and a third expansion chamber,
Since at least four expansion chambers are provided, the silencing effect due to the expansion of exhaust gas is increased compared to the conventional one.

In addition, a pair of second expansion chambers are provided so as to branch from the first expansion chamber, and when exhaust gas flows from these second expansion chambers to the third expansion chamber, a pair of communication ports face each other. In the third expansion chamber, the exhaust gas flows collide with each other, and the sound energy of each exhaust gas interferes, thereby achieving more effective muffling.

[Example] The present invention will be explained below based on embodiments shown in the drawings.

First, FIGS. 1 to 5 show an embodiment in which the present invention is applied to a so-called water jet propulsion device for a small boat. In FIGS. 1 and 2, an engine 12 is disposed within a hull 10 of this small boat, and a rotor blade 14 is driven by an impeller shaft 13 extending from the engine 12. As a result, seawater is sucked into the tact 15 from the bottom of the ship and discharged from the nozzle 16, thereby obtaining thrust. In FIG. 2, reference numeral 17 indicates a stator vane provided on the downstream side of the rotor blade 14. A water intake port of a cooling water intake pipe 18 is opened at this position, and the cooling water is passed through the cooling water intake pipe 18 to the engine 12. At the same time, the water is introduced into the exhaust system of the engine from the cooling water jacket of the engine 12 via the cooling water hose 20. Note 21
is an electrical box and 1. A control device that electrically controls the engine 12 and the like are housed.

Referring to FIG. 3, the exhaust boat for each cylinder of the engine 12 (
Exhaust from the engine 12 (not shown) passes through an exhaust manifold 22 extending diagonally downward from the engine 12 body, joins here, passes through a rising exhaust pipe 23 connected to the exhaust manifold 22, and is sent upward. This exhaust pipe 2
3 is guided to a large-diameter exhaust pipe 24 extending substantially horizontally from the upper end of the exhaust pipe 3 . The large diameter exhaust pipe 24 functions as an expansion chamber. The exhaust pipes 23 and 24 have a double pipe structure, and the inner pipe 25
The cooling water after cooling the engine 12 flows into the space between the inner pipe 25 and the outer pipe 26 through the cooling water hose 2.
0 (see Figure 2) to cool the exhaust gas.

The exhaust gas expanded in the large-diameter exhaust pipe 24 is guided from the rising outlet 27 of the inner pipe 25 to the exhaust hose 28, and is sent to the exhaust silencer 32 disposed at the front position of the hull 30 as shown in FIG. It will be done. Note that the cooling water after cooling the exhaust gas in the exhaust pipe 24 also passes through the exhaust hose 28, merges with the exhaust gas, and is sent to the exhaust silencer 32.

As shown in FIGS. 3 to 5, the exhaust silencer 32 includes a first partition plate 36 that extends in the longitudinal direction of the casing 34 and a first partition plate 36 that extends in the longitudinal direction of the casing 34 in the casing 34 that forms a box-shaped outer wall. a pair of second partition plates 3 extending to
8, a first expansion chamber 40, a pair of second expansion chambers 42, and a third expansion chamber 44 are defined. - The pair of second expansion chambers 42 each have a first partition plate 36
It communicates with the first expansion chamber 40 through a pair of first M ports 46 formed in the , and is arranged in parallel to the first expansion chamber 40 with the third expansion chamber 44 sandwiched therebetween. Each second expansion chamber 42 has a second expansion chamber formed in a pair of second partition plates 38, respectively.
It communicates with the third expansion chamber 44 via a communication port 48 . The first communication port 46 and the second communication port 48 are located above the respective partition plates, and both the W42 communication ports 48 are arranged to face each other. Furthermore, the first expansion chamber 4
0 and each second expansion chamber 42 are formed by a small hole 50 provided at the lower end of the first partition plate 36, and each second expansion chamber 42 and third expansion chamber 44 are formed at the lower end of each second partition plate 38. They are also communicated by small holes 52 provided, and these small holes 50.52
functions as a water passage at low speeds.

The exhaust gas and cooling water that meet in the exhaust hose 28 are led into the first expansion chamber 40 via the inlet pipe 58. Inlet pipe 58
has a bent portion 56 that extends substantially horizontally near the entrance portion 54 and then bends downward to open downward.

Reference numeral 60 denotes an outlet pipe having an inlet 61 that opens downward, and the exhaust air and some of the water in the third expansion chamber 44 are taken out from the exhaust silencer 32 through the outlet 63 of the outlet pipe 60. , from the exhaust hose 62, through an exhaust pipe 64 extending rearward along the hull 30, and from an exhaust outlet 64a at the rear end of the hull 30 (see FIG. 2); In FIG. 5, reference numeral 66 indicates a cushioning mat interposed between the casing 34 and the hull 30 of the exhaust silencer 32.

The water level of the cooling water accumulated at the bottom of each expansion chamber becomes low during engine operation due to the high exhaust pressure acting on the upstream expansion chamber (see Figure 3), and when the engine is running at low speed, the water level in the upstream expansion chamber becomes low. The air flows sequentially from the (i+1)th expansion chamber to the third expansion chamber on the downstream side through each of the small holes 50, 52. When the engine is running at high speed, the exhaust pressure is high, so the cooling water is pumped into the first intake port 46 near the top of each partition wall along with the exhaust gas.
, flows from the second communication port 48 to the downstream expansion chamber.

The exhaust gas is expanded and muffled in the first expansion chamber 40, a portion of the cooling water accumulates at the bottom of the expansion chamber 40, and a portion of medium and high speed operation flows together with the exhaust gas through a pair of first communication ports 46. It is branched and introduced into the pair of second expansion chambers 42 . each second
The exhaust gas is expanded again in the expansion chamber 42, and a portion of the water likewise accumulates at the bottom of this expansion chamber, while the other portion is introduced into the third expansion chamber 44 through each of the second communication ports 48 together with the exhaust gas. Ru. The exhaust gas is expanded again in this third expansion chamber 44, and some water accumulates at the bottom thereof.

As described above, the exhaust gas is repeatedly expanded in at least four expansion chambers when passing through the exhaust silencer 32, so that sufficient exhaust noise is silenced. Furthermore, the exhaust is connected to a pair of second
[A pair of second electrodes disposed opposite to each other from the expansion chamber 42
Since it is introduced into the third expansion chamber 44 through the communication port 48,
The exhaust gases passing through the second communication port 48 interfere with each other, further increasing the silencing effect. In particular, in the above embodiment,
The exhaust gas introduced into the third expansion chamber 44 at medium and high speeds also contains cooling water, and since this cooling water also interferes and scatters, the silencing effect of the exhaust gas is dramatically improved.

Note that the water accumulated in the third expansion chamber 44 is then passed through the outlet pipe 60 by the exhaust pressure in the third expansion chamber 44 to the exhaust pipe 6.
It is discharged to 4. Accordingly, the water level in the third expansion chamber 44 is pushed down and returns to the level of the inlet 61 of the outlet pipe 60. That is, the inlet 61 of the outlet pipe 60 has a function of setting the water level in the third expansion chamber 44.

By the way, the exhaust silencing device 32 not only has an exhaust silencing function, but also
It has a water backflow prevention function that prevents water from entering the engine through the exhaust passage.

When water flows back from the ship's exhaust outlet 84a due to waves or the like, the water flowing back from the small exhaust outlet 64a accumulates in the third expansion chamber 44, which has a relatively large bottom area.

In other words, the rise in the water level in the third expansion chamber 44 due to backflow water is suppressed to a small level. In addition, the second communication port 48, the first communication port
: Since the J46 is arranged above the second partition plate 38 and the Ml partition plate 36, it is possible to prevent water from instantaneously flowing back through the second communication port 48 and the first communication port 46, and Because the opening area of small holes 50 and 52 for low speed is small,
Similarly, water is difficult to flow back to the E flow side.

The water surface around the ship is marked A in Figure 3 when the ship is sailing at full throttle.
Even if it is in the position shown by , it rises to the position shown by the symbol B when the ship is stopped, so there is a risk that the water level in the third expansion chamber 44 will rise when the ship is stopped. Therefore, it is more effective to prevent water backflow by setting the height Hl from the position B to the exhaust outlet of the ship and the height H2 from the position B to the outlet 63 of the outlet pipe 60 sufficiently high. 0 In this embodiment, the rising outlet 27 is set higher than H2 to enhance the water backflow prevention function.

Further, in the embodiment, the inlet portion 54 of the inlet pipe 58
That is, since the inlet of the first expansion chamber 40 is located higher than the inlet 61 of the outlet pipe 60, that is, the outlet of the third expansion chamber 44 (see FIG. 3), water is prevented from flowing back into the engine 12. This can be prevented more reliably.

Furthermore, since the inlet pipe 58 is provided with a bent portion 56 that curves downward, when the boat overturns, the opening of this bent portion 56 will open upward at a higher position, thus preventing exhaust gas. Water accumulating in the silencer 32 or the engine 12
It has a function that prevents water from flowing back into the body.

Next, FIG. 6 shows another embodiment of the present invention, and this embodiment differs from the previous embodiment in that at least each second partition plate 38 is provided with a plurality of communication ports 68. The point is that it is made of punched metal plate. With this configuration, the sound energy is attenuated by the so-called throttling effect when the exhaust gas passes through the plurality of communication ports 68, and the exhaust gases interfere with each other as in the previous embodiment, so that the silencing effect is dramatically increased. Further, according to this embodiment, there is no major obstruction to the flow of exhaust gas, and therefore a reduction in engine output can be prevented.

Next, FIG. 7 shows still another embodiment of the present invention, in which, for example, the first partition plate 36 is arranged diagonally, in contrast to the above-described embodiment shown in FIG. , the volumes are made different between the pair of second Wg expansion chambers 42, thereby doubling the number of sound frequency ranges that are muffled when passing through the second expansion chambers 42 compared to the previous embodiment. There is.

Further, each path length 1r from the time when the exhaust gas is introduced into the first expansion chamber 40 from the inlet pipe 58 until it is branched and introduced into the third expansion chamber 44 through a pair of second expansion chambers 42. , fLz are made different from each other, thereby shifting the phase of the compression waves of the exhaust sound when introduced into the third expansion chamber 44 from the two-temperature communication port 48, and re-exhausting or colliding with each other, thereby changing the phase of the compression waves of the exhaust sound. This creates interference from dense waves to more effectively muffle the sound.

[Effects] As explained above, according to the present invention, at least four exhaust expansion chambers are formed.

Moreover, since the communication ports from the pair of second expansion chambers to the third expansion chamber are arranged opposite to each other, the exhaust gases passing through these ports interfere with each other, thereby providing an excellent effect of improving the noise reduction effect.

[Brief explanation of drawings]

Fig. 1 is a side view showing a water jet type small boat as an example to which the present invention is applied, Fig. 2 is a cross-sectional view showing the internal structure of Fig. 1, and Fig. 3 is a cross-sectional view of Fig. 2. FIG. 4 is an enlarged sectional view taken along line IV-IT in FIG. 3, FIG. 5 is a sectional view taken along line v-V in FIG. 4, and FIG. 6 is another embodiment of the present invention. FIG. 7 is a sectional view taken at the same position as FIG. 4 showing still another embodiment of the present invention. 12--Engine, 32--Exhaust silencer 40
...First expansion chamber, 42-...Second expansion chamber 44...Third expansion chamber, 46.48-...Tsunichi Nitto 4 Figure 5

Claims (1)

[Claims] (1) A first expansion chamber into which exhaust gas from the engine is introduced;
a pair of second expansion chambers each communicating with the first expansion chamber; and a third expansion chamber having a pair of communication ports facing each other and communicating with the pair of second expansion chambers via the pair of communication ports. An exhaust silencing device for marine propulsion equipment.